聊聊hikari与tomcat jdbc pool的fail fast

本文主要研究在中途数据库挂的情况下,hikari与tomcat jdbc pool的fail fast情况。

实验代码

    @Test
    public void testDatabaseDownAndUp() throws SQLException, InterruptedException {
        LOGGER.info("begin to wait for database down and up");

        for(int c=0;c<10;c++){
            LOGGER.info("execute:"+(c+1));
            Connection conn = null;

            String sql = "select 1";
            PreparedStatement pstmt = null;
            try {
                long start = System.currentTimeMillis();
                conn = dataSource.getConnection();
                LOGGER.info("{} got connection,cost:{}",(c+1),System.currentTimeMillis() - start);
                pstmt = (PreparedStatement)conn.prepareStatement(sql);
                ResultSet rs = pstmt.executeQuery();
                int col = rs.getMetaData().getColumnCount();
                while (rs.next()) {
                    for (int i = 1; i <= col; i++) {
                        System.out.print(rs.getObject(i));
                    }
                    System.out.println("");
                }
                LOGGER.info("============================");
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                //close resources
                DbUtils.closeQuietly(pstmt);
                DbUtils.closeQuietly(conn);
            }

            TimeUnit.SECONDS.sleep(10);
        }
    }

在第一次循环输出之后断开数据库连接,等个二三十秒再恢复。

hikari

2018-01-30 15:35:16.668  INFO 5852 --- [           main] c.e.demo.HikariDemoApplicationTests      : execute:1
2018-01-30 15:35:26.854  INFO 5852 --- [           main] c.e.demo.HikariDemoApplicationTests      : execute:2
2018-01-30 15:36:06.867  INFO 5852 --- [           main] c.e.demo.HikariDemoApplicationTests      : execute:3
2018-01-30 15:36:46.878  INFO 5852 --- [           main] c.e.demo.HikariDemoApplicationTests      : execute:4

从这点来看,中途数据库断开的话,hikari会不断获取数据库链接 假设数据库一直没恢复,那么所以请求数据库操作的业务线程将都阻塞connectionTimeout的时间,这个会占用工作线程 hikari只有testOnBorrow功能,是直接一个while循环,在timeout时间内不断borrow连接,validate连接,validate成功才返回或者超时抛出SQLTransientConnectionException异常。borrow的超时时间为connectionTimeout,默认30秒。

validate不成功日志记录的异常

2018-01-31 16:45:00.653  WARN 6501 --- [           main] org.postgresql.jdbc.PgConnection         : Validating connection.

org.postgresql.util.PSQLException: FATAL: terminating connection due to administrator command
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2422) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2167) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:306) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:441) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:365) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:155) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.jdbc.PgPreparedStatement.executeUpdate(PgPreparedStatement.java:132) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.jdbc.PgConnection.isValid(PgConnection.java:1364) ~[postgresql-42.2.1.jar:42.2.1]
    at com.zaxxer.hikari.pool.PoolBase.isConnectionAlive(PoolBase.java:160) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:171) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:147) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:123) [HikariCP-2.7.6.jar:na]
    at com.example.demo.HikariDemoApplicationTests.testDatabaseDownAndUp(HikariDemoApplicationTests.java:109) [test-classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_71]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_71]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_71]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_71]
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) [junit-4.12.jar:4.12]
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12]
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) [junit-4.12.jar:4.12]
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:73) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:83) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190) [spring-test-5.0.3.RELEASE.jar:5.0.3.RELEASE]
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137) [junit-4.12.jar:4.12]
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69) [junit-rt.jar:na]
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234) [junit-rt.jar:na]
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74) [junit-rt.jar:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_71]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_71]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_71]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_71]
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na]

假设在测试之前新建立好maxPoolSize的连接,那么执行之后中断数据库,则下一次的getConnection会挨个取出这些空闲连接,validate,validate失败会在log里头记录异常,同时getConnection继续循环获取连接

getConnection timeout抛出的异常

java.sql.SQLTransientConnectionException: demo1 - Connection is not available, request timed out after 60007ms.
    at com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:666)
    at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:182)
    at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:147)
    at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:123)
    at com.example.demo.HikariDemoApplicationTests.testDatabaseDownAndUp(HikariDemoApplicationTests.java:98)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:73)
    at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:83)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: org.postgresql.util.PSQLException: Connection to 192.168.99.100:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:247)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:49)
    at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:195)
    at org.postgresql.Driver.makeConnection(Driver.java:452)
    at org.postgresql.Driver.connect(Driver.java:254)
    at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:117)
    at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:123)
    at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:375)
    at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:204)
    at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:459)
    at com.zaxxer.hikari.pool.HikariPool.access$200(HikariPool.java:70)
    at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:696)
    at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:682)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at org.postgresql.core.PGStream.<init>(PGStream.java:69)
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:158)
    ... 16 more

循环获取连接超时,则抛出SQLTransientConnectionException

异步线程PoolEntryCreator补充新连接在日志记录的异常

2018-01-31 16:45:00.915  WARN 6501 --- [onnection adder] unknown.jul.logger                       : ConnectException occurred while connecting to 192.168.99.100:5432

java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_71]
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_71]
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_71]
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_71]
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_71]
    at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_71]
    at org.postgresql.core.PGStream.<init>(PGStream.java:69) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:158) ~[postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:49) [postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:195) [postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.Driver.makeConnection(Driver.java:452) [postgresql-42.2.1.jar:42.2.1]
    at org.postgresql.Driver.connect(Driver.java:254) [postgresql-42.2.1.jar:42.2.1]
    at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:117) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:123) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:375) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:204) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:459) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.pool.HikariPool.access$200(HikariPool.java:70) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:696) [HikariCP-2.7.6.jar:na]
    at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:682) [HikariCP-2.7.6.jar:na]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_71]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_71]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_71]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_71]

获取连接的源码

HikariCP-2.7.6-sources.jar!/com/zaxxer/hikari/pool/HikariPool.java

   /**
    * Get a connection from the pool, or timeout after the specified number of milliseconds.
    *
    * @param hardTimeout the maximum time to wait for a connection from the pool
    * @return a java.sql.Connection instance
    * @throws SQLException thrown if a timeout occurs trying to obtain a connection
    */
   public Connection getConnection(final long hardTimeout) throws SQLException
   {
      suspendResumeLock.acquire();
      final long startTime = currentTime();

      try {
         long timeout = hardTimeout;
         do {
            PoolEntry poolEntry = connectionBag.borrow(timeout, MILLISECONDS);
            if (poolEntry == null) {
               break; // We timed out... break and throw exception
            }

            final long now = currentTime();
            if (poolEntry.isMarkedEvicted() || (elapsedMillis(poolEntry.lastAccessed, now) > ALIVE_BYPASS_WINDOW_MS && !isConnectionAlive(poolEntry.connection))) {
               closeConnection(poolEntry, poolEntry.isMarkedEvicted() ? EVICTED_CONNECTION_MESSAGE : DEAD_CONNECTION_MESSAGE);
               timeout = hardTimeout - elapsedMillis(startTime);
            }
            else {
               metricsTracker.recordBorrowStats(poolEntry, startTime);
               return poolEntry.createProxyConnection(leakTaskFactory.schedule(poolEntry), now);
            }
         } while (timeout > 0L);

         metricsTracker.recordBorrowTimeoutStats(startTime);
         throw createTimeoutException(startTime);
      }
      catch (InterruptedException e) {
         Thread.currentThread().interrupt();
         throw new SQLException(poolName + " - Interrupted during connection acquisition", e);
      }
      finally {
         suspendResumeLock.release();
      }
   }

tomcat

2018-01-30 15:39:23.913  INFO 5894 --- [           main] com.example.JpaDemoApplicationTests      : execute:1
2018-01-30 15:39:33.939  INFO 5894 --- [           main] com.example.JpaDemoApplicationTests      : execute:2
2018-01-30 15:39:43.949  INFO 5894 --- [           main] com.example.JpaDemoApplicationTests      : execute:3
2018-01-30 15:39:53.955  INFO 5894 --- [           main] com.example.JpaDemoApplicationTests      : execute:4
2018-01-30 15:40:03.962  INFO 5894 --- [           main] com.example.JpaDemoApplicationTests      : execute:5
2018-01-30 15:40:13.968  INFO 5894 --- [           main] com.example.JpaDemoApplicationTests      : execute:6

tomcat jdbc pool有testOnBorrow,testOnReturn,testOnConnect,testWhileIdle属性来配置什么时候检测连接,如果是testOnBorrow的话,有空闲连接则进行borrow同时进行validate,如果上一次validate的时间在validation interval内,则默认validate成功,否则进行validate,validate失败会进行reconnect,再validate,如果再失败则抛出new SQLException(“Failed to validate a newly established connection.”)。如果没有空闲连接,且连接池没满就创建一个新的;如果没有空闲连接且连接池满了,则while轮询空闲队列,如果没取到连接,若没超过maxWait则继续,超过则抛出PoolExhaustedException。如果没有空闲连接,且连接池满了,则borrow超时时间为maxWait默认30秒。 这个示例程序,每次循环都会先归还连接再sleep,因此连接池始终有空闲连接,只是testOnBorrow校验不成功,进行了reconnect,在reconnect抛出了异常

reconnect抛出的异常

org.postgresql.util.PSQLException: Connection to 192.168.99.100:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:262)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:51)
    at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:215)
    at org.postgresql.Driver.makeConnection(Driver.java:404)
    at org.postgresql.Driver.connect(Driver.java:272)
    at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:310)
    at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:203)
    at org.apache.tomcat.jdbc.pool.PooledConnection.reconnect(PooledConnection.java:361)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:821)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:651)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:198)
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:132)
    at com.example.JpaDemoApplicationTests.testDatabaseDownAndUp(JpaDemoApplicationTests.java:296)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at org.postgresql.core.PGStream.<init>(PGStream.java:61)
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:144)
    ... 44 more

获取连接的源码

tomcat-jdbc-8.5.23-sources.jar!/org/apache/tomcat/jdbc/pool/ConnectionPool.java

    /**
     * Thread safe way to retrieve a connection from the pool
     * @param wait - time to wait, overrides the maxWait from the properties,
     * set to -1 if you wish to use maxWait, 0 if you wish no wait time.
     * @param username The user name to use for the connection
     * @param password The password for the connection
     * @return a connection
     * @throws SQLException Failed to get a connection
     */
    private PooledConnection borrowConnection(int wait, String username, String password) throws SQLException {

        if (isClosed()) {
            throw new SQLException("Connection pool closed.");
        } //end if

        //get the current time stamp
        long now = System.currentTimeMillis();
        //see if there is one available immediately
        PooledConnection con = idle.poll();

        while (true) {
            if (con!=null) {
                //configure the connection and return it
                PooledConnection result = borrowConnection(now, con, username, password);
                borrowedCount.incrementAndGet();
                if (result!=null) return result;
            }

            //if we get here, see if we need to create one
            //this is not 100% accurate since it doesn't use a shared
            //atomic variable - a connection can become idle while we are creating
            //a new connection
            if (size.get() < getPoolProperties().getMaxActive()) {
                //atomic duplicate check
                if (size.addAndGet(1) > getPoolProperties().getMaxActive()) {
                    //if we got here, two threads passed through the first if
                    size.decrementAndGet();
                } else {
                    //create a connection, we're below the limit
                    return createConnection(now, con, username, password);
                }
            } //end if

            //calculate wait time for this iteration
            long maxWait = wait;
            //if the passed in wait time is -1, means we should use the pool property value
            if (wait==-1) {
                maxWait = (getPoolProperties().getMaxWait()<=0)?Long.MAX_VALUE:getPoolProperties().getMaxWait();
            }

            long timetowait = Math.max(0, maxWait - (System.currentTimeMillis() - now));
            waitcount.incrementAndGet();
            try {
                //retrieve an existing connection
                con = idle.poll(timetowait, TimeUnit.MILLISECONDS);
            } catch (InterruptedException ex) {
                if (getPoolProperties().getPropagateInterruptState()) {
                    Thread.currentThread().interrupt();
                }
                SQLException sx = new SQLException("Pool wait interrupted.");
                sx.initCause(ex);
                throw sx;
            } finally {
                waitcount.decrementAndGet();
            }
            if (maxWait==0 && con == null) { //no wait, return one if we have one
                if (jmxPool!=null) {
                    jmxPool.notify(org.apache.tomcat.jdbc.pool.jmx.ConnectionPool.POOL_EMPTY, "Pool empty - no wait.");
                }
                throw new PoolExhaustedException("[" + Thread.currentThread().getName()+"] " +
                        "NoWait: Pool empty. Unable to fetch a connection, none available["+busy.size()+" in use].");
            }
            //we didn't get a connection, lets see if we timed out
            if (con == null) {
                if ((System.currentTimeMillis() - now) >= maxWait) {
                    if (jmxPool!=null) {
                        jmxPool.notify(org.apache.tomcat.jdbc.pool.jmx.ConnectionPool.POOL_EMPTY, "Pool empty - timeout.");
                    }
                    throw new PoolExhaustedException("[" + Thread.currentThread().getName()+"] " +
                        "Timeout: Pool empty. Unable to fetch a connection in " + (maxWait / 1000) +
                        " seconds, none available[size:"+size.get() +"; busy:"+busy.size()+"; idle:"+idle.size()+"; lastwait:"+timetowait+"].");
                } else {
                    //no timeout, lets try again
                    continue;
                }
            }
        } //while
    }

小结

如果是没有空闲连接且连接池满不能新建连接的情况下

  • hikari则是阻塞connectionTimeout的时间,没有得到连接抛出SQLTransientConnectionException
  • tomcat jdbc pool会阻塞max-wait时间,若没有得到连接则抛出PoolExhaustedException

如果是有空闲连接的情况

  • hikari是在connectionTimeout时间内不断循环获取下一个空闲连接进行校验,校验失败继续获取下一个空闲连接,直到超时抛出SQLTransientConnectionException
  • tomcat jdbc pool会borrow连接然后validate连接,正常validate失败会reconnect,再validate,若此时reconnect不成功则抛出ConnectException: Connection refused,如果reconnect成功但是validate失败,则抛出SQLException(“Failed to validate a newly established connection.”)

假设数据库是挂的,但还有空闲连接,tomcat的testOnBorrow=true。对比可以发现

hikari在获取一个连接的时候,会在connectionTimeout时间内循环把空闲连接挨个validate一次,最后timeout抛出异常;之后的获取连接操作,则一直阻塞connectionTimeout时间再抛出异常 tomcat jdbc pool则是在获取一个连接的时候,先borrow出来连接,正常validate失败会reconnect,再validate,通常reconnect的时候抛出了ConnectException: Connection refused,然后业务程序会fail fast,之后的获取连接也都是fail fast的

由此可见,hikari如果connectionTimeout如果设置太大的话,在数据库挂的时候,很容易阻塞业务线程,而tomcat jdbc pool则会fail fast。

另外hikari是异步去建立minIdle大小的连接,而tomcat是同步的建立initial-size的连接。

原文发布于微信公众号 - 码匠的流水账(geek_luandun)

原文发表时间:2018-02-04

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